Introduction
Jelutong wood, the Standard Malaysian Name for the wood of Dyera spp. (Apocynaceae), is widely known and used across Peninsular Malaysia, Sabah, and Sarawak. This versatile timber includes major species like D. costulata and D. polyphylla. Its sapwood and heartwood are indistinguishable, both presenting a creamy white to pale straw color.
Density
Jelutong wood is classified as a Light Hardwood, with an air-dry density of 420-500 kg/m³.
Natural Durability
Jelutong wood is not durable when exposed to outdoor conditions. Standard graveyard tests by the Forest Research Institute Malaysia (FRIM) showed that untreated D. costulata specimens were destroyed within six months in one test, and had an average service life of 1.4 years in another. The timber is highly susceptible to powder-post beetles, termites, and blue stain in its green state.
Preservative Treatment
Jelutong wood is highly receptive to preservative treatments, significantly enhancing its durability.
Texture
Jelutong wood has a moderately fine and even texture, with an almost straight grain.
Strength Properties
Jelutong wood falls into Strength Group D (Engku, 1988b) or SG 6 (MS 544:Part 2:2001).
| Test Condition | Modulus of Elasticity (MPa) | Modulus of Rupture (MPa) | Compression parallel to grain (MPa) | Compression perpendicular to grain (MPa) | Shear Strength (MPa) |
|—————-|—————————–|—————————|————————————-|——————————————-|———————–|
| Green | 7,900 | 38.0 | 21.0 | 1.9 | 5.0 |
| Air dry | 8,100 | 50.0 | 27.0 | 2.7 | 6.0 |
Machining Properties
Jelutong wood is easy to saw and plane, producing smooth surfaces despite its softness.
| Test Condition | Sawing | Planning | Boring | Turning |
|—————-|——–|———-|——–|———|
| Green | easy | easy | easy | – |
| Air dry | easy | easy | easy | easy |
Nailing Property
The nailing property of Jelutong wood is excellent.
Air Drying
Jelutong wood seasons quickly without serious degradation, except for staining and powder-post beetle attacks. Dipping the timber in preservatives immediately after sawing helps mitigate these issues. 13 mm thick boards take 1.5 months to air dry, while 38 mm thick boards take 3 months.
Kiln-Drying
Kiln Schedule H is recommended for Jelutong.
| Moisture Content (%) | Temperature (Dry Bulb) | Temperature (Wet Bulb) | Relative Humidity (%) |
|———————-|————————|————————|———————–|
| Green | 135°F (57°C) | 127°F (53°C) | 80 |
| 50 | 135°F (57°C) | 126°F (52°C) | 75 |
| 40 | 140°F (60°C) | 126°F (52°C) | 65 |
| 30 | 150°F (65.5°C) | 129°F (54°C) | 55 |
| 20 | 170°F (76.5°C) | 136°F (58°C) | 40 |
Shrinkage
Jelutong wood exhibits low shrinkage, with radial shrinkage averaging 0.8% and tangential shrinkage averaging 2%.
Movement in Service
The movement of seasoned timber is classified as Type II.
Defects
Jelutong wood logs are generally free from common defects. However, wood logs damaged by improper tapping or left in the forest after felling are susceptible to fungal and insect infestations, including sap-stain fungi and ambrosia beetles. Freshly sawn wood is also prone to mold, blue stain, and insect attacks, sometimes occurring just hours after sawing.
Uses
Jelutong wood is highly valued for pencil manufacturing. It is also suitable for:
– Plywood
– Packing boxes and crates
– Pattern making
– Carving works
– Disposable chopsticks
– Toothpicks
– Picture frames
– Drawing boards
– Blackboards
– Battery separators
– Toys
– Wooden shoe heels
Jelutong wood’s versatility and workability make it a preferred choice for many applications. At Creatimber, we proudly supply Jelutong wood and other timber varieties to the Malaysian market and beyond, exporting to Asia, Europe, North America, and more. Explore our extensive range of timber products and discover how Creatimber can elevate your next project.
